C1 LD94330C1_RTO4 - Illuminating Engineering Society

PHOTOS: JILL CODY
The Kachel Fieldhouse includes recreational
multipurpose courts and a competition 200 meter
running track. Our design addresses the lighting
requirements of various sports, while meeting
rigorous sustainable design objectives.
Managing Glare
After establishing the architectural design to provide an adequate
level of daylight, the next step focused on assessing and
resolving problems with glare. Direct sun or a very bright diffuse
surface in a athlete’s field of view were central concerns.
Diffuse glazing is one
technique for controlling
direct sun, but it
AWELL-CONDITIONED ATHLETE
HGA and The Weidt Group partner to create
an efficient home for athletics
Aspace for athletic competition and recreation,
efficient and simple to operate, with
design features making it a model for
future facilities. Simply put, these were the goals of
the design team and owner.
The DLK/Kachel Fieldhouse addition to the
Williams Center at the University of Wisconsin –
Whitewater was designed to create an intercollegiate
competition facility for indoor track meets
and to expand recreational and intramural space
for students on campus and the surrounding
community. The project was also designated to
establish a model design process for incorporating
sustainable design elements into this and
future projects for the State of Wisconsin. To this
end, the architects and engineers at Hammel,
Green and Abrahamson (HGA) worked with
energy consultants The Weidt Group and State of
Wisconsin facilities development personnel to
develop energy savings strategies that included
reduced energy consumption for lighting loads
and the use of daylighting.
Daylighting Design
It was once said by a wise man that daylighting
is like taking a sip of water from a fire hydrant.
The sun is a powerful light source so bright that
it can seldom be used directly for most interior
visual environments unless controlled properly.
The best source of daylight is from the sky, not the
sun, so glazing orientations for a building need to
maximize the facades where the sunlight can be
easily controlled. The north orientation, and then
the south, are desirable in northern latitudes,
while east and west facades are problematic due
to low sun angles, and are difficult to control costeffectively.
During design, several variations on architectural
roof forms and fenestration alternatives were
studied using physical daylight models and energy
simulation software. Among the alternatives studied:
flat roof vs. barrel vaulted; Low-E clear glazing
vs. translucent, insulating glazing (e.g. Kalwall);
active and passive sunlight control features; and
the use of skylights. Vertical fenestration was evaluated
on various combinations of the north, south,
and west faces of the building. The east face of the
building was not evaluated because it abuts the
existing building.
Several of the passive sunlight control features
under consideration, including internal light
shelves and redirecting glass block, were eliminated
due to their associated construction costs. Some
glazing placements and types were eliminated due
to unacceptable glare created by direct sunlight hitting
the playing surfaces during large periods of the
year, while others were eliminated due to owner
preferences.
The architectural design finally selected was a
barrel vault roof with translucent, insulating glazing
on the north, south and west faces. Based on
physical scale-model measurements, the barrel
vault roof form provided 35 percent greater daylight
levels in the center of the fieldhouse compared
to a flat roof configuration. This was due to
the increase in window height on the north and
south walls compared to the flat roof. Adding glazing
high along the west wall increased daylight
levels further, improving daylight uniformity from
north to south.
36 LD+A/March 2003 www.iesna.org
glare by creating an extremely
bright surface when exposed to
direct sunlight. Using low visible
light transmittance (VLT)
glazing can reduce surface
brightness. However, low VLT
glazing also reduces the
amount of interior daylight
available throughout the year.
Historic weather information
for Whitewater, Wisconsin
showed that a significant percentage
of days could be
expected to be overcast.
Selecting VLT characteristics at
this building site became a balancing
act between reducing
glare during sunny conditions
and depressed interior daylight
levels during the majority of the
time it is overcast.
Instead of selecting a “one
size fits all” approach to balancing
the VLT needs on the
project, a customized approach
was used, “tuning” the VLT to
the requirements of each façade
orientation, balancing the
(top) Three translucent
clerestories allow playing
surfaces to be washed with 5-15
footcandles of natural light
on a partly cloudy day.
(bottom) Visible light
transmittance values were
carefully selected to take
advantage of the available
daylight without creating
discomfort glare for players using
basketball and tennis courts.
www.iesna.org
still presents the
potential to produce
impacts of glare, interior light level, and energy performance.
On the west window wall a very low VLT (15 percent) was
selected to ensure the diffuse surface would not be too bright
within the field of view of the multi-sport playing courts. The
south windows with an overhang had less exposure to sunlight
throughout the year, allowing a higher value of VLT (35
percent). On the north, transparent glass could have worked,
but to maintain architectural consistency, diffuse glazing with
the highest available VLT (50 percent) for the glazing product
selected was used.
LD+A/March 2003 37